Maynard, MA, USA: Beacon-Villager newspaper column on local history, observations on nature and recreational activities, plus an occasional health-related article. Columns from 2009-11 collected into book "MAYNARD: History and Life Outdoors." Columns from 2012-14 collected into book "Hidden History of Maynard." - David A. Mark

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Wednesday, May 20, 2015

A Murder of Crows

We know to say “pride of lions, gaggle of geese, school of
fish,” but why? As it turns out, social standing among Medieval European
nobility required that men should know their venery – the proper naming of
groups of animals – else be taken for crass and uneducated. Collections of
these terms culminated in a master list compiled in The Book of St. Albans, in
1486. The term “A murder of crows” dates back at least that far, but
unfortunately without any historic explanation as to why “murder.”

Anyone delving into the history of venery should consult "An Exaltation of Larks," by Jame Lipton. Older versions of "murder of crows" were written as "mursher of crowys" and "murther of crowes." The 'murther' (or 'murthre') spelling was common into the 1600s but is now archaic. Similarly, 'crawe' was Old English and 'crowe' Middle English before evolving into 'crow.'

From Alfred Hitchcock's "The Birds." Crows were trained to fly
to the jungle gym. Special effects crows were added to make the
number of birds larger than it actually was.

Crows do gather. One of the key scenes in Alfred Hitchcock’s
movie, The Birds, cuts back and forth between the inside of a small school and
the progressively larger number of crows gathering on the playground equipment
outside. In real life, when crows happen upon an owl they will sound an alarm
call that draws other crows from miles around. The resultant mob of crows, all
cawing loudly, will harass the owl until it leaves the area. Crows will also
mob hawks. It sounds very much as if the crows intend bloody murder, and
perhaps that led to the historic term.

An oft-mentioned folklore on “murder” is that a group of
crows can decide to turn on one of their own, pecking it to death. The truth in
this is debatable. A solitary crow happening upon a crow family’s space will be
set on, but driven away, not killed. These attacks can be many-against-one
because families are more than just the mated pair. Offspring from the previous
year or two stay near their parents and help with feeding and defending the new
babies.

During the spring/summer nesting season families are scattered,
but in fall and winter crows prefer to congregate, especially at night.
Foraging flocks of 10 to 50 will start to cluster as evening nears, then fly to
join other flocks in a preferred night roosting area, where numbers can be as
high as in the thousands. In northern regions these tree roosts may be in parks
and cemeteries within cities; the thinking being that the winter temperatures
in cities are slightly warmer than in the surrounding countryside, and also
that the ambient night light of cities discourages marauding owls.

Locally, the population of crows has been impacted by West
Nile Virus (WNV). The virus is endemic and non-lethal in many species of birds
in Africa and the Middle East. It was first
detected in the United
States in 1999, in wild crows living at the
Bronx Zoo. WNV then rapidly spread across the continent. Mosquitoes are the
major vector, but raptors and scavengers can become infected by eating ill or
dead animals. The viral strain that reached North America
was particularly lethal to crows. The
crow population in Massachusetts
is half of what it was fifteen years ago. There is evidence that the negative
impact of WNV is stabilizing in recent years, with some states showing recovery
from the lowest bird counts.

WNV also infects people. Most will have no
symptoms. About 20 percent will develop fever, headache, muscle ache, nausea or
skin rash (risk of symptoms increases with age). Less than one percent will
develop a severe illness. In Massachusetts
there were fewer than ten cases reported each year for 2013 and 2014.

WNV is not the only bird virus troubling the U.S.
Apparently, wild ducks or geese migrating overhead over chicken and turkey
farms in the mid-west have caused an avian flu epidemic. Tens of millions of
birds are either dead, dying or else being euthanized to prevent spread of H5N2
avian virus to other farms. The risk of human cross-infection from this strain
of virus is very, very low, but do expect to be paying higher prices for eggs,
chicken and turkey for months to come. And pet food, too, as laying hens, when culled for declining egg production, end up in cat and dog food.